Cooling system for an internal combustion engine

Abstract

A cooling system for an internal combustion engine is disclosed which includes a coolant pump for circulating a coolant in a coolant circuit and a radiator disposed in the coolant circuit. A charged-air cooler is disposed in the coolant circuit downstream of the radiator, and a long-route exhaust-gas-recirculation cooler disposed in the coolant circuit downstream of the charged-air cooler and upstream of the radiator.

What is claimed is: 
     
       1. A cooling system for an internal combustion engine comprising:
 a coolant pump for circulating a coolant in a coolant circuit; 
 a radiator disposed in the coolant circuit; 
 a charged-air cooler disposed in the coolant circuit downstream of the radiator; 
 a long-route exhaust-gas-recirculation cooler disposed in the coolant circuit downstream of the charged-air cooler and upstream of the radiator; and 
 an electronic control unit configured to control a coolant temperature at a coolant inlet of the long-route exhaust-gas-recirculation cooler by regulating a mass flow rate of the coolant circulating in the coolant circuit, 
 wherein the electronic control unit is configured to:
 determine a coolant temperature at a coolant inlet of the charged-air cooler; 
 determine a mass flow rate of air through the charged-air cooler; 
 determine an air temperature difference between an air inlet and an air outlet of the charged-air cooler; 
 calculate a desired value of the coolant mass flow rate on the basis of the coolant temperature at the coolant inlet of the charged-air cooler, of the air mass flow rate, of the air temperature difference, and of a target value of the coolant temperature at the inlet of the long-route exhaust-gas-recirculation cooler; and 
 regulate the coolant mass flow rate according to the desired value. 
 
 
     
     
       2. The cooling system according to  claim 1 , further comprising a cooler for a diesel-exhaust-fluid injector disposed in the coolant circuit downstream of the charged-air cooler and upstream of the long-route exhaust-gas-recirculation cooler. 
     
     
       3. The cooling system according to  claim 1 , wherein the electronic control unit is configured to control the coolant temperature at the coolant inlet of the long-route exhaust-gas-recirculation cooler to be higher than a predetermined threshold value thereof. 
     
     
       4. The cooling system according to  claim 3 , wherein the coolant temperature threshold value is comprised between 45° C. and 55° C. 
     
     
       5. The cooling system according to  claim 1 , wherein the electronic control unit is configured to regulate the coolant mass flow rate by varying a speed of the coolant pump. 
     
     
       6. A method of operating a cooling system for an internal combustion engine comprises:
 circulating a coolant with a coolant pump in a coolant circuit having a radiator, a charged-air cooler disposed in the coolant circuit downstream of the radiator, and a long-route exhaust-gas-recirculation cooler disposed in the coolant circuit downstream of the charged-air cooler and upstream of the radiator; and 
 controlling a coolant temperature at a coolant inlet of the long-route exhaust-gas-recirculation cooler by regulating a mass flow rate of the coolant circulating in the coolant circuit, wherein the regulating the mass flow rate comprises:
 determining a coolant temperature at a coolant inlet of the charged-air cooler; 
 determining a mass flow rate of air through the charged-air cooler; 
 determining an air temperature difference between an air inlet and an air outlet of the charged-air cooler; 
 calculating a desired value of the coolant mass flow rate on the basis of the coolant temperature at the coolant inlet of the charged-air cooler, of the air mass flow rate, of the air temperature difference, and of a target value of the coolant temperature at the inlet of the long-route exhaust-gas-recirculation cooler; and 
 regulating the coolant mass flow rate according to the desired value. 
 
 
     
     
       7. A computer program comprising a computer code suitable for performing the method according to  claim 6  stored on a non-transitory computer readable medium. 
     
     
       8. A computer program product comprising a computer which when programmed with the computer code of  claim 7  operating a cooling system for an internal combustion engine.